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August 31, 2007

Strange But True!

Q. Penguins are big these days, especially with other penguins. But they've got a problem. After diving into the water and eating, an emperor penguin must return to its home and locate its mate among thousands of other penguins huddled together to avoid freezing in the harsh Antarctic winter. Besides, all penguins look much the same, even to other penguins, whose underwater-adapted vision likely leaves them nearsighted in the air. How then does Mr. Penguin find the Mrs., or vice versa?

A. Most birds vocalize with only one side of their vocal organ (syrinx) but penguins use both simultaneously, with each side setting up a different frequency, says Jearl Walker in “The Flying Circus of Physics.” These form a strong net sound wave, plus a warble that varies from loud to soft and a beat frequency based on the difference between the two actual frequencies. Thus a penguin's cry can be rich with distinctive resonances and beats, allowing it to be recognized even among a thousand other penguin voices.


 
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